Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Five muscarinic receptor genes (m1–m5) that encode distinct muscarinic receptor subtypes have been cloned. Because of their structural homology and pharmacological similarity, ligand binding probes currently available do not clearly distinguish among the subtypes. To obtain a clear distribution within the CNS of molecularly defined muscarinic receptor subtypes, seven brain regions were examined for the expression of the respective mRNAs. The most sensitive method for detecting mRNA is through amplification of the respective cDNAs. Brain regions were obtained from male Wistar rats, and total RNA was isolated. The isolates were extensively treated with RNase-free DNase to remove any residual genomic DNA. Total RNA (1 µg) was reverse-transcribed using random primers and reverse transcriptase. The resulting cDNA was amplified using a thermal cycler, and the polymerase chain reaction (PCR)-amplified products were analyzed by gel electrophoresis containing ethidium bromide and visualized with fluorescent illumination. PCR-amplified samples were also injected directly onto an HPLC anion exchange column and quantified by UV detection. Each of the five muscarinic subtypes was found in every brain region examined. The m1 subtype was most abundant in cortex and gradually declined in content caudally to the spinal cord. The m2 subtype was most abundant in thalamus-hypothalamus and pons-medulla. The m4 subtype was found in greatest amount in the striatum, whereas m3 and m5 were expressed consistently throughout the CNS. The combination of RT-PCR and HPLC provides a rapid and sensitive method for quantifying the expression of mRNA coding for all five muscarinic receptor subtypes derived from the CNS.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1527-3458
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The pharmacological effects of the tobacco-derived alkaloid nicotine have been widely studied in humans and animals for decades. However, relatively little attention has been given to the potential actions of its major metabolite, cotinine. After nicotine consumption the duration of cotinine's presence in blood and brain greatly exceeds that of nicotine. Therefore, cotinine could mediate the more protracted pharmacological effects of nicotine. The studies described in this report were thus designed to further investigate certain neuropharmacological actions of cotinine. Behavioral tests (e.g., delayed matching-to-sample) were conducted in aged rhesus monkeys to assess the effects of cotinine on working memory and attention. In rats a prepulse inhibition (PPI) procedure was used to assess the effects of the compound on auditory gating — a method for predicting the potential antipsychotic properties of drugs. Cotinine exhibited significant effectiveness in these tasks. The drug was also cytoprotective in differentiated PC-12 cells with a potency equivalent to that of nicotine. The effects of chronic cotinine treatment on the expression of nicotinic and muscarinic acetylcholine receptors in rat brain were measured by [125I]epibatidine, [125I]α-bungarotoxin ([125I]BTX), [3H]pirenzepine ([3H]PRZ), and [3H]AFDX-384 ([3H]AFX) autoradiography. Unlike nicotine, cotinine failed to upregulate the expression of brain nicotinic receptors. Based on its relative safety in man, cotinine should prove useful in the treatment of diseases of impaired cognition and behavior without exhibiting the toxicity usually attributed to nicotine.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1527-3458
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Focused microwave irradiation was employed to stabilize endogenous whole rat brain bradykinin levels prior to a simple extraction procedure. Skull microwave exposure (2450 MHz, 3.8 kW., 2.45 sec) resulted in inactivation to less than 5% of control of whole brain kallikrein and kininase activity. Using this adequate exposure duration whole rat brain kinin levels as measured by a sensitive radio-immunoassay were approximately 0.6 pmol/g (wet weight). Further purification of irradiated brain extracts using HPLC revealed that immunoreactive kinin eluted as a single peak that co-chromatographed with authentic bradykinin. Microwave fixation duration of 1.25 sec yielded greatly increased levels of immunoreactive kinin which following HPLC purification eluted in two peaks, corresponding to authentic bradykinin and T-kinin, respectively. The tissue injury resulting from incomplete microwave fixation resulted in the release of kinins. This excess immunoreactive kinin may be derived from cerebral blood, since the predominant form of kinin-generating protein in plasma is T-kininogen.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-2072
    Keywords: Key words Learning and memory ; Serotonin ; Cholinergic ; Monkey ; Pharmacokinetics ; Receptor binding ; Alzheimer’s disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recent evidence indicates that the 5-HT4 subtype of serotonin receptor may modulate central cholinergic activity in regions of the mammalian CNS important to memory such as the frontal cortex, hippocampus and amygdala. These receptors could represent targets for drugs designed for the symptomatic therapy of Alzheimer’s disease (AD) and other disorders of memory. In the present study, the binding activity of RS 17017 (previously described as a selective 5-HT4 agonist) was assessed across a number of neurotransmitter receptors and binding sites, pharmacokinetic data were obtained, and the compound was evaluated in macaques for mnemonic effects via a computer-assisted delayed matching-to-sample task (DMTS). Binding data confirmed the 5-HT4 selectivity of the compound, while pharmacokinetic results revealed low oral bioavailability, but a large volume of distribution of the compound. Significant and reproducible improvements in DMTS accuracy were observed after oral administration of the compound across a dose-effect series in both younger and older monkeys. The results suggest that RS 17017 offers a potential for memory enhancement in disorders involving cognitive decline, and are consistent with a role for central 5-HT4 receptors in memory. Improvements in DMTS performance in aged monkeys may have particular implications for neurodegenerative conditions such as AD, whereas positive results in the younger monkeys indicate that RS 17017 (or similar compounds) may have additional potential in the therapeutics of memory disorders not necessarily associated with advanced age.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-6903
    Keywords: Hypertension ; brain ; choline uptake ; cholinergic neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The high-affinity uptake of choline (HAChU) by freshly prepared crude synaptosomal fractions was employed as relative measure of regional brain cholinergic activity. TheV max for uptake as determined by the accumulation of a tracer amount of3H-choline in the presence of unlabeled choline (0.2–2 μM) varied 6 fold depending upon the region examined (striatum〉hypothalamus〉medulla-pons). HAChU was hemicholinium-3-sensitive and linear at 37°C from 1 to 8 min in all brain regions. Respective brain synaptosomal fractions derived from adult (12 week old) spontaneously hypertensive (SH) rats and normotensive Wistar Kyoto (WK) rats revealed no difference in theV max for HAChU from synaptosomes derived from the striatum of either strain. However, there was a significant increase in theV max for HAChU measured from the medulla-pons of SH rats compared with WK rats. In older (22 weeks) rats, theV max for HAChU was 78% greater than age-matched WK control rats. In addition, a highly significant correlation was found between resting systolic blood pressure and theV max for HAChU both in the medulla-pons (r=0.76) and hypothalamus (r=0.48). That the increase in HAChU in SH rats was not a consequence of elevated pressure, was indicated by the lack of effect of prolonged i.v. infusion of pressor agents in normotensive rats on HAChU. These findings are consistent with a role for brain cholinergic neurons in the maintenance of hypertension in SH rats.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...